Technical Field
[0001] The present invention relates to a sealing member having slidability.
Background Art
[0002] Rubber is suitable as a sealing member because it is capable of ensuring a sealing
property by its own rubber elasticity (repulsive force). Meanwhile, rubber has a high
coefficient of friction due to its viscoelastic properties, and therefore has no slidability.
For this reason, in order to seal between sliding members accompanied by relative
sliding by using rubber, it is necessary to improve the slidability of the rubber.
[0003] In general, a lubricant such as a resin is used to improve the slidability of rubber.
For example, the slidability of rubber can be improved by coating the surface of the
rubber with the lubricant (see, for example, Patent Literature 1). Further, there
is also a technology for improving the slidability of rubber by dispersing a lubiricant
in the rubber.
Citation List
Patent Literature
[0004] Patent Literature 1: Japanese Patent Application Laid-open No.
1995-227935
Disclosure of Invention
Technical Problem
[0005] Fluorine rubber is excellent in heat resistance, oil resistance, and chemical resistance,
and has a performance that is different from that of another synthetic rubber such
as nitrile rubber. For this reason, a sealing member formed of fluorine rubber can
be used for various purposes. Then, it is desired to use fluorine rubber for also
a sealing member for sealing between sliding members.
[0006] However, the fluorine rubber has very high lubricity with respect to a general lubricant
unlike other synthetic rubbers. For this reason, it is difficult to directly apply,
to the fluorine rubber, the above-mentioned technology for improving the slidability
of rubber by using the lubricant.
[0007] That is, even if the surface of the fluorine rubber is coated with a lubricant, the
lubricant is not well retained on the surface of the fluorine rubber, and thus is
easily peeled from the surface of the fluorine rubber. Further, it is difficult to
disperse, in the fluorine rubber, a lubricant having a sufficient amount to improve
the slidability of the fluorine rubber.
[0008] In view of the circumstances as described above, it is an object of the present invention
to provide a ring-shaped sealing member having both the sealing property and slidability.
Solution to Problem
[0009] In order to achieve the above-mentioned object, a sealing member according to an
embodiment of the present invention is formed in a ring shape and has a sliding surface.
[0010] The sealing member includes: 100 parts by weight of fluorine rubber; and 0.5 to 50
(inclusive) parts by weight of a particulate resin.
[0011] The particulate resin includes a compatible portion and a lubrication portion, the
compatible portion having compatibility with the fluorine rubber, the lubrication
portion having lubricity with respect to the fluorine rubber.
[0012] A Shore A hardness measured using the sliding surface as a pressing surface is not
less than 80.
[0013] The particulate resin may be present on the sliding surface.
[0014] In this sealing member, since rubber elasticity is achieved by the fluorine rubber,
a favorable sealing property can be realized.
[0015] Further, it is possible to impart high slidability to the sealing member by the action
of the lubrication portion of the particulate resin. Further, this sealing member
has high durability because the particulate resin is hard to be removed from the surface
of the sealing member by the action of the compatible portion of the particulate resin.
[0016] Therefore, this sealing member has both the sealing property and slidability.
[0017] The particulate resin may be dispersed in the fluorine rubber.
With this configuration, by the action of the particulate resin dispersed in the fluorine
rubber, the slidability of the sealing member is ensured even in the case where the
sliding surface is worn.
[0018] The particulate resin may contain not less than 40 weight% of silicone.
With this configuration, the slidability of the sealing member is further improved.
[0019] The particulate resin may be formed by a silicone-acrylic copolymer.
With this configuration, the high slidability of the sealing member is maintained
for a long time.
[0020] The seal member may further include carbon distributed in the fluorine rubber.
With this configuration, a sealing member having appropriate hardness can be obtained.
[0021] A surface roughness Rz of a counterpart material on which the sliding surface slides
may be not less than 0.5 z and not more than 18.0 z in accordance with JIS B 6001-1982.
[0022] The surface roughness Rz of the sliding surface may be not less than 0.5 z and not
more than 10.0 z in accordance with JIS B 6001-1982.
[0023] The sliding surface may include no parting line. In the sealing member having such
a configuration, a more favorable sealing property and slidability can be achieved.
Advantageous Effects of Invention
[0024] As described above, in accordance with the present invention, it is possible to provide
a ring-shaped sealing member having both the sealing property and slidability.
Brief Description of Drawings
[0025]
[Fig. 1] Fig. 1 is a schematic diagram showing a cross section of a composition for
a sealing member according to an embodiment of the present invention.
[Fig. 2] Fig. 2 is a schematic diagram showing a cross section of a particulate resin
of the composition for a sealing member.
[Fig. 3A] Fig. 3A is a schematic diagram showing a cross section of the composition
for a sealing member during molding.
[Fig. 3B] Fig. 3B is a schematic diagram showing a cross section of the composition
for a sealing member during molding.
[Fig. 3C] Fig. 3C is a schematic diagram showing a partial cross section of a sealing
member obtained by molding the composition for a sealing member.
[Fig. 4] Fig. 4 is a graph showing an example of a result of a slidability test of
the sealing member.
[Fig. 5A] Fig. 5A is a plan view of the sealing member formed in a ring shape.
[Fig. 5B] Fig. 5B is a cross-sectional view of the sealing member taken along the
line A-A' in Fig. 5A.
[Fig. 6] Fig. 6 is a cross-sectional view showing an operation of incorporating the
sealing member into a shaft and a housing.
[Fig. 7] Fig. 7 is a cross-sectional view showing the state where the sealing member
is incorporated into the shaft and the housing.
[Fig. 8] Fig. 8 is a graph showing an example of an infrared spectrum obtained as
a result of infrared absorption analysis of the sealing member.
[Fig. 9] Fig. 9 is a graph showing an example of a result of a slidability test of
the sealing member. Mode(s) for Carrying Out the Invention
[0026] Hereinafter, an embodiment of the present invention will be described with reference
to the drawings.
1. Schematic Configuration
[0027] Fig. 1 is a schematic diagram showing a partial cross section of a composition 10
for a sealing member according to this embodiment. The composition for a sealing member
10 is configured as a raw material for producing a sealing member 20 (see Fig. 3C
and Figs. 5A to 7). That is, the sealing member 20 is obtained by molding the composition
for a sealing member 10.
[0028] The composition for a sealing member 10 includes an uncrosslinked fluorine rubber
component 11 and a particulate resin 12. The particulate resin 12 is particulate (powdered),
and uniformly dispersed in the fluorine rubber component 11. The particulate resin
12 is configured as a lubrication component of the composition for a sealing member
10.
[0029] Fig. 2 is a schematic diagram showing an enlarged cross section of the particulate
resin 12. Note that although the particulate resin 12 is shown in a spherical shape
in Figs 1 and 2, the shape of the particulate resin 12 can be arbitrarily changed.
Further, although all the particulate resins 12 have similar shapes in Figs. 1 and
2, the shape of each of the particulate resins 12 may differ.
[0030] The particulate resin 12 includes a compatible portion 12a having compatibility with
fluorine rubber, and a lubrication portion 12b having lubricity with respect to the
fluorine rubber. Note that although the compatible portion 12a and the lubrication
portion 12b are shown separated in one direction in Fig. 2, the particulate resin
12 is not limited to such a configuration.
[0031] For example, the compatible portion 12a and the lubrication portion 12b may be distributed
throughout the particulate resin 12. Further, the particulate resin 12 may have a
configuration in which the compatible portion 12a is dispersed in the lubrication
portion 12b or, conversely, a configuration in which the lubrication portion 12b is
dispersed in the compatible portion 12a.
[0032] Here, assumption is made that a particulate resin includes only the lubrication portion
12b, i.e., the particulate resin does not include the compatible portion 12a. This
particulate resin does not having compatibility with the fluorine rubber component
11, i.e., has only lubricity with respect to the fluorine rubber component 11, and
therefore tends to be separated from the fluorine rubber component 11.
[0033] Therefore, even if such a particulate resin is tried to be dispersed in the fluorine
rubber component 11, the particulate resin cannot remain in the fluorine rubber component
11 and is ejected out of the fluorine rubber component 11. For this reason, it is
difficult to disperse such a particulate resin in the fluorine rubber component 11.
[0034] In this regard, the particulate resin 12 according to this embodiment includes the
compatible portion 12a in addition to the lubrication portion 12b. Therefore, the
particulate resin 12 is capable of remaining in the fluorine rubber component 11 due
to the action of the compatible portion 12a. For this reason, it is possible to uniformly
disperse the particulate resin 12 in the fluorine rubber component 11.
[0035] Note that in the process of producing the composition for a sealing member 10, it
is favorable to knead a small amount of the fluorine rubber component 11 with respect
to the particulate resin 12 before dispersing the particulate resin 12 in the fluorine
rubber component 11. As a result, the dispersibility of the particulate resin 12 with
respect to the fluorine rubber component 11 is further improved.
[0036] Figs. 3A to 3C are each a cross-sectional view schematically showing a method of
producing the sealing member 20 using the composition for a sealing member 10. The
composition for a sealing member 10 is molded as the sealing member 20 by an arbitrary
method. Examples of the method of molding the composition for a sealing member 10
include an injection molding method, an extrusion molding method, and a press molding
method.
[0037] Fig. 3A shows the state where a mold M is filled with the composition for a sealing
member 10. The particulate resin 12 is uniformly dispersed in the fluorine rubber
component 11 in the mold M. The shape of the mold M is determined in accordance with
the shape of the sealing member 20, and the sealing member 20 having an arbitrary
shape can be produced from the composition for a sealing member 10.
[0038] Fig. 3B shows the state where the composition for a sealing member 10 deposited in
the mold M is heated. By heating the composition for a sealing member 10, crosslinking
(primary vulcanization) of the fluorine rubber component 11 proceeds. Along with this,
the particulate resin 12 dispersed in the fluorine rubber component 11 moves toward
the surface due to the action of the lubrication portion 12b.
[0039] As a result, at least a part of the particulate resin 12 bleed out on the surface
of the fluorine rubber component 11. The particulate resins 12 that have bleed out
on the surface of the fluorine rubber component 11 are bonded to each other and integrated
to form a surface layer portion 23 (see Fig. 3C) covering the fluorine rubber component
11.
[0040] When crosslinking of the fluorine rubber component 11 further progresses, the particulate
resin 12 does not move. After the crosslinking of the fluorine rubber component 11
is finished, a molded body is taken out from the mold M. By performing secondary vulcanization
on this molded body as necessary, the sealing member 20 is obtained.
[0041] Fig. 3C shows the sealing member 20 produced by molding the composition for a sealing
member 10. The sealing member 20 includes a body portion 22 and the surface layer
portion 23. The body portion 22 constitutes the shape of the sealing member 20. The
surface layer portion 23 covers the surface of the body portion 22.
[0042] The body portion 22 is formed mainly of a fluorine rubber 21 produced by crosslinking
the fluorine rubber component 11 contained in the composition for a sealing member
10. Further, in the body portion 22, the particulate resin 12 that has remained without
bleeding on the surface of the fluorine rubber component 11 at the time of crosslinking
is dispersed in the fluorine rubber 21.
[0043] The fluorine rubber 21 is excellent in heat resistance, oil resistance, and chemical
resistance. For this reason, the sealing member 20 in which the body portion 22 is
mainly formed of the fluorine rubber 21 is excellent in heat resistance, oil resistance,
and chemical resistance. Therefore, the sealing member 20 achieves high durability
in various applications.
[0044] Since the surface layer portion 23 is obtained by bonding the particulate resin 12,
it includes the compatible portion 12a having compatibility with the fluorine rubber
21 and the lubrication portion 12b having lubricity with respect to the fluorine rubber
21. The surface layer portion 23 typically has a configuration in which the compatible
portion 12a and the lubrication portion 12b are distributed throughout the surface
layer portion 23.
[0045] The surface layer portion 23 formed on the surface of the sealing member 20 has high
slidability due to the action of the lubrication portion 12b that is a self-lubricating
component. Therefore, the sealing member 20 can achieve high slidability that cannot
be achieved by only the fluorine rubber 21 because the surface layer portion 23 functions
as a solid lubricating film.
[0046] Further, the surface layer portion 23 can achieve a high adhesion force of the surface
layer portion 23 to the body portion 22 (fluorine rubber 21) by the action of the
compatible portion 12a. As a result, the surface layer portion 23 has high durability
because it becomes hard to peel from the body portion 22. Therefore, the sealing member
20 maintains high slidability for a long time.
[0047] Further, in the sealing member 20, the particulate resin 12 is caused to bleed out
at the time of molding to form the surface layer portion 23. Thus, even in a complicated
shape, it is possible to easily form the surface layer portion 23 in the entire area
of the surface of the body portion 22 without a gap. As a result, the sealing member
20 achieves high slidability more reliably.
[0048] In addition, in the sealing member 20, since the particulate resin 12 is dispersed
in the body portion 22, the particulate resin 12 is present on the surface of the
body portion 22. Therefore, even in the case where the surface layer portion 23 is
worn and the body portion 22 is exposed, the sealing member 20 is capable of ensuring
slidability.
[0049] Note that in the sealing member 20, in the case where it is sufficient that high
slidability by the surface layer portion 23 is obtained, the particulate resin 12
does not need to be dispersed in the body portion 22. That is, all the particulate
resins 12 contained in the composition for a sealing member 10 may form the surface
layer portion 23 of the sealing member 20.
[0050] Further, in the sealing member 20, the particulate resin 12 only needs to be present
on the surface thereof, and the particulate resin 12 does not necessarily need to
form the film-shaped surface layer portion 23. That is, the sealing member 20 does
not necessarily need to have a configuration in which the body portion 22 and the
surface layer portion 23 can be clearly distinguished from each other.
[0051] Further, in the sealing member 20, the particulate resin 12 only needs to be present
on the surface thereof, and it does necessarily need to cause the particulate resin
12 to bleed out at the time of molding. In this case, in the sealing member 20, the
concentration of the particulate resin 12 may be approximately the same between the
surface and the inside, or the concentration of the particulate resin 12 may be higher
inside than on the surface.
2. Detailed Configuration
2.1 Sealing Member 20
2.1.1 Surface Layer Portion 23 and Particulate Resin 12
[0052] The resin forming the surface layer portion 23 and the particulate resin 12 of the
sealing member 20 only needs to be a resin including the compatible portion 12a having
compatibility with the fluorine rubber 21, and the lubrication portion 12b having
lubricity with respect to the fluorine rubber 21. The configuration of the compatible
portion 12a and the lubrication portion 12b in such a resin is not limited to a specific
one.
[0053] As an example, a silicone resin, which has favorable slidability and a main skeleton
of silicone having low surface energy, can be used as the resin forming the surface
layer portion 23 and the particulate resin 12. In the silicone resin, the main skeleton
of silicone becomes a self-lubricating component, and functions as the lubrication
portion 12b.
[0054] The silicone forming the silicone resin is not limited to a specific type one. Specific
examples thereof include dimethyl silicone, methylphenyl silicone, amino-modified
silicone, and epoxy-modified silicone.
[0055] Further, in the silicone resin, the configuration that functions as the compatible
portion 12a may be bonded to the main skeleton of silicone. The configuration that
functions as the compatible portion 12a only needs to have compatibility with the
fluorine rubber 21, and can be realized by using, for example, various functional
groups or various resins (e.g., acrylic resin).
[0056] The silicone resin favorably contains 40 weight% or more of silicone in order to
achieve sufficient lubricity. As a result, sufficiently high slidability can be achieved
in the surface layer portion 23. Further, a sufficient amount of the particulate resin
12 bleeds out at the time of molding of the sealing member 20, and thus, the surface
layer portion 23 is favorably formed.
[0057] The silicone resin imparted with compatibility with the fluorine rubber 21 can be
selected from commercially available products depending on the application of the
sealing member 20, or the like. For example, such a silicone resin can be selected
from Chaline (registered trademark) series, which is a silicone-acrylic copolymer
manufactured by Nissin Chemical Industry Co., Ltd.
2.1.2 Fluorine Rubber 21
[0058] The fluorine rubber 21 constituting the body portion 22 of the sealing member 20
is not limited to a specific one as long as it is rubber containing a fluorine atom.
As the fluorine rubber 21, for example, vinylidene fluoride fluororubber (FKM) mainly
formed of vinylidene fluoride can be used.
[0059] More specifically, as the binary fluorine rubber 21, for example, vinylidene fluoride-hexafluoropropylene-,
vinylidene fluoride-chlorotrifluoroethylene-, tetrafluoroethylene-perfluoro-, or tetrafluoroethylene-propylene-based
one can be used.
[0060] As the ternary fluorine rubber 21, for example, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene-,
vinylidene fluoride-perfluoroalkyl vinyl ether-tetrafluoroethylene-, or tetrafluoroethylene-propylene-vinylidene
fluoride-based one can be used. These ternary fluorine rubbers 21 are generally excellent
in cold resistance.
[0061] Further, as the fluorine rubber 21, a single type one may be used or a plurality
of types may be combined for use. The degree of polymerization of the fluorine rubber
21 can be determined in accordance with the application of the sealing member 20 or
the like so that an appropriate sealing property or slidability can be achieved.
2.1.3 Additive
[0062] The body portion 22 of the sealing member 20 may contain an additive other than the
fluorine rubber 21 and the particulate resin 12 as necessary. For example, the body
portion 22 may contain a curing agent for increasing the hardness as an example. As
the curing agent, for example, powdery carbon (carbon black or the like) can be used.
[0063] Further, the body portion 22 may contain various additives such as a filler, a reinforcing
material, and a pigment other than the curing agent.
2.2 Composition for Sealing Member 10
2.2.1 Fluorine Rubber Component 11 and Particulate Resin 12
[0064] The configuration of the fluorine rubber component 11, and the particulate resin
12 in the composition for a sealing member 10 is determined in accordance with the
configuration of the sealing member 20. The content of the particulate resin 12 in
the composition for a sealing member 10 is not less than 0.5 parts by weight and not
more than 50 parts by weight on the basis of 100 parts by weight of the fluorine rubber
component 11.
[0065] By setting the content of the particulate resin 12 to not less than 0.5 parts by
weight, a sufficient amount of the particulate resin 12 bleeds out at the time of
molding, and thus, the favorable surface layer portion 23 is formed. Further, by keeping
the content of the particulate resin 12 at not more than 50 parts by weight, a favorable
sealing property can be easily achieved by the action of the fluorine rubber 21 in
the sealing member 20.
[0066] Further, from the same viewpoint, the content of the particulate resin 12 in the
composition for a sealing member 10 is favorably not less than 1 part by weight and
not more than 20 parts by weight on the basis of 100 parts by weight of the fluorine
rubber component 11. As a result, the sealing member 20 having both more favorable
slidability and a more favorable sealing property can be achieved.
2.2.2 Additive
[0067] Also the additive in the composition for a sealing member 10 is determined in accordance
with the configuration of the sealing member 20. That is, the composition for a sealing
member 10 may contain the curing agent described above. Further, the composition for
a sealing member 10 may contain various additives such as a filler, a reinforcing
material, and a pigment other than the curing agent.
[0068] Further, the composition for a sealing member 10 may contain a crosslinking agent
for crosslinking the fluorine rubber component 11 in advance. The crosslinking agent
is not limited to a specific one. For example, the crosslinking agent can be selected
from commercially available crosslinking agents. As the crosslinking agent, for example,
a polyamine crosslinking-, polyol crosslinking-, or peroxide crosslinking-based one
can be used.
[0069] Further, the composition for a sealing member 10 may contain a processing aid. Examples
of the processing aid include a fatty acid such as stearic acid and fatty acid metal
salt. However, the processing aid hinders the movement of the particulate resin 12
during crosslinking of the fluorine rubber component 11, i.e., hinders formation of
the surface layer portion 23 in some cases.
[0070] From such a viewpoint, the amount of the processing aid is favorably small. Specifically,
it is favorable to keep the amount of the processing aid at not more than 3 parts
by weight on the basis of 100 parts by weight of the fluorine rubber component 11.
Further, it is more favorable that the composition for a sealing member 10 does not
substantially contain a processing aid. Specifically, it is more favorable that the
amount of the processing aid is kept at not more than 0.1 parts by weight.
[0071] In addition, the composition for a sealing member 10 may contain various additives
such as a crosslinking aid and a retarder as necessary.
3. Examples and Comparative Examples
[0072] Hereinafter, Examples and Comparative Examples of this embodiment will be described.
However, the present invention is not limited to the configuration described below.
Note that the same fluorine rubber component 11 is used in also any of Examples and
Comparative Examples described below.
3.1 Examples 1-1 to 1-5, Comparative Examples 1-1 to 1-12
3.1.1 Sample according to Example 1-1
[0073] In Example 1-1, as the particulate resin 12 of the composition for a sealing member
10, one (lubricant 1) having the content of silicone of 70 weight% among Chaline (registered
trademark) series manufactured by Nissin Chemical Industry Co., Ltd. was used. In
Example 1-1, the content of the particulate resin 12 was set to 20 parts by weight
on the basis of 100 parts by weight of the fluorine rubber component 11.
[0074] In Example 1-1, after kneading the composition for a sealing member 10 having the
above-mentioned configuration, it was molded by the primary vulcanization at 170°C
for 10 minutes into a spherical shape of 20 mm in outer diameter. Subsequently, secondary
vulcanization was performed at 230°C for 4 hours on the spherical molded body. As
a result, a sample of the sealing member 20 was obtained.
3.1.2 Samples according to Examples 1-2 to 1-5
[0075] In Examples 1-2 to 1-5, samples of the sealing member 20 were prepared using the
composition for a sealing member 10 in which the configuration of the particulate
resin 12 is different from that of the composition for a sealing member 10 used in
Example 1-1. Conditions for preparing each sample of the sealing member 20 according
to Examples 1-2 to 1-5 were the same as that in Example 1-1.
[0076] In Examples 1-2 to 1-5, the content of the particulate resin 12 (lubricant 1) is
different from that of Example 1-1. Specifically, the content of the particulate resin
12 on the basis of 100 parts by weight of the fluorine rubber component 11 was 10
parts by weight in Example 1-2, 5 parts by weight in Example 1-3, 1 part by weight
Example 1-4, and 0.5 parts by weight in Example 1-5.
3.1.3 Samples according to Comparative Examples 1-1 to 1-12
[0077] In Comparative Examples 1-1 to 1-12, samples of a sealing member were prepared using
a composition for a sealing member having a configuration different from that of the
composition for a sealing member 10 according to this embodiment. Conditions for preparing
the samples of a sealing member according to Comparative Examples 1-1 to 1-12 were
the same as that in Example 1-1.
[0078] In Comparative Examples 1-1 and 1-2, the content of the particulate resin 12 (lubricant
1) is less than that in this embodiment. Specifically, in Comparative Example 1-1,
the content of the particulate resin 12 on the basis of 100 parts by weight of the
fluorine rubber component 11 was 0.1 parts by weight. In Comparative Example 1-2,
the content of the particulate resin 12 is 0 parts by weight, i.e., the particulate
resin 12 is not used.
[0079] In Comparative Example 1-3, instead of the particulate resin 12 according to this
embodiment, silicone oil (lubricant 2) was used. However, since the silicone oil has
high lubricity with respect to the fluorine rubber component 11, it has been separated
without being mixed with the fluorine rubber component 11. As a result, no sample
of a sealing member was obtained in Comparative Example 1-3.
[0080] In Comparative Examples 1-4 to 1-12, samples of a sealing member were prepared using
a composition for a sealing member containing a lubricant having a configuration different
from that of the particulate resin 12 according to this embodiment. The configuration
of the lubricant used in Comparative Examples 1-4 to 1-12 is different from that of
the particulate resin 12 in that it does not include at least one of the compatible
portion 12a and the lubrication portion 12b.
[0081] In Comparative Examples 1-4 to 1-6, respectively, lubricants 3 to 5, which were general
lubricants, were used. In Comparative Examples 1-7 to 1-12, respectively, lubricants
6 to 11, which were general processing aids (such as mold release agents) having a
lubricity function, were used. Specifically, the lubricants 3 to 11 used in Comparative
Examples 1-4 to 1-12 are as follows.
Lubricant 3: Oleic acid amide ("Armoslip CP" manufactured by Lion Corporation.)
Lubricant 4: Teflon powder
Lubricant 5: Mixed lubricant mainly formed of fatty acid calcium salt ("Struktol WB16"
manufactured by S&S Japan Co., LTD.)
Lubricant 6: Fatty acid zinc salt ("Exton L-2" manufactured by Kawaguchi Chemical
Industry Co., LTD.)
Lubricant 7: Mixing agent of fatty acid metal salt and fatty acid glyceride ("Exton
L-7" manufactured by Kawaguchi Chemical Industry Co., LTD.)
Lubricant 8: Aluminum stearate and calcium stearate
Lubricant 9: Paraffin-type special wax ("Suntight S" manufactured by Seiko Chemical
Co.,Ltd.)
Lubricant 10: Methyl cellulose
Lubricant 11: Stearylamine ("FARMIN 80T" manufactured by Kao Corporation.)
3.1.4 Evaluation of Each Sample
[0082] A slidability test was conducted on the samples obtained in Examples 1-1 to 1-5 and
Comparative Examples 1-1, 1-2, and 1-4 to 1-12. As a counterpart material to be slid,
a plate material having a surface roughness Ra of 0.4 µm, on which hard chrome plating
was performed, was used. The slidability test was conducted in a state where each
sample was sandwiched with the counterpart material and compressed by 40%.
[0083] In the slidability test, a sample sandwiched with the counterpart material was placed
on a testing machine (Autograph manufactured by Shimadzu Corporation.), and the resistance
value (load) when the center part of the sample pushed in at a speed of 50 mm/min
in the direction along the surface of the counterpart material was measured. As a
result, for example, a graph as shown in Fig. 4 is obtained.
[0084] Fig. 4 is a graph showing an example of the result of the slidability test. In Fig.
4, the results obtained for the samples according to Example 1-2 and Comparative Example
1-2 are shown. It can be seen that in the example according to Example 1-2, the resistance
value after starting sliding is lower than that of the sample according to Comparative
Example 1-2.
[0085] The slidability of each sample was evaluated on the basis of the resistance value
when the sample was pushed in by 10 mm. The evaluation criteria of slidability of
each sample were A to D shown below.
- A: Resistance value is not more than 40N.
- B: Resistance value is not more than 50N.
- C: Resistance value is not more than 70N.
- D: Resistance value exceeds 70N.
[0086] Table 1 shows the evaluation results of the slidability of the samples according
to Examples 1-1 to 1-5 and Comparative Examples 1-1, 1-2, and 1-4 to 1-12. Note that
regarding Comparative Example 1-3 in which a sample of a sealing member was not obtained,
the slidability was not evaluated. Further, Table 1 shows the content (parts by weight)
of each component of each sample.
[Table 1]
|
Example 1-1 |
Example 1-2 |
Example 1-3 |
Example 1-4 |
Example 1-5 |
Comparative Example 1-1 |
Comparative Example 1-2 |
Comparative Example 1-3 |
Comparative Example 1-4 |
Comparative Example 1-5 |
Comparative Example 1-6 |
Comparative Example 1-7 |
Comparative Example 1-8 |
Comparative Example 1-9 |
Comparative Example 1-10 |
Comparative Example 1-11 |
Comparative Example 1-12 |
Fluorine rubber component |
100 |
100 |
100 |
100 |
100 |
100 |
100 |
100 |
100 |
100 |
100 |
100 |
100 |
100 |
100 |
100 |
100 |
Carbon |
70 |
70 |
70 |
70 |
70 |
70 |
70 |
70 |
70 |
70 |
70 |
70 |
70 |
70 |
70 |
70 |
70 |
Lubricant 1 |
20 |
10 |
5 |
1 |
0.5 |
0.1 |
|
|
|
|
|
|
|
|
|
|
|
Lubricant 2 |
|
|
|
|
|
|
|
10 |
|
|
|
|
|
|
|
|
|
Lubricant 3 |
|
|
|
|
|
|
|
|
10 |
|
|
|
|
|
|
|
|
Lubricant 4 |
|
|
|
|
|
|
|
|
|
10 |
|
|
|
|
|
|
|
Lubricant 5 |
|
|
|
|
|
|
|
|
|
|
10 |
|
|
|
|
|
|
Lubricant 6 |
|
|
|
|
|
|
|
|
|
|
|
10 |
|
|
|
|
|
Lubricant 7 |
|
|
|
|
|
|
|
|
|
|
|
|
10 |
|
|
|
|
Lubricant 8 |
|
|
|
|
|
|
|
|
|
|
|
|
|
10 |
|
|
|
Lubricant 9 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
10 |
|
|
Lubricant 10 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
10 |
|
Lubricant 11 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
10 |
Slidability |
A |
A |
A |
B |
C |
D |
D |
- |
D |
D |
D |
D |
D |
D |
D |
D |
D |
[0087] As shown in Table 1, in any of the samples according to Examples1-1 to 1-5 in which
the content of the particulate resin 12 on the basis of 100 parts by weight of the
fluorine rubber component 11 was not less than 0.5 parts by weight, the resistance
value was not less than 70 N and favorable slidability was achieved. Therefore, it
was confirmed that the sealing member 20 according to this embodiment, favorable slidability
was achieved.
[0088] Further, in Examples 1-1 to 1-4 in which the content of the particulate resin 12
was not less than 1 part by weight on the basis of 100 parts by weight of the fluorine
rubber component 11, the resistance value was not more than 50 N and more favorable
slidability was achieved. Therefore, it is favorable that the content of the particulate
resin 12 in the composition for a sealing member 10 is not less than 1 part by weight.
[0089] Further, in Examples 1-1 to 1-3 in which the content of the particulate resin 12
was not less than 5 parts by weight on the basis of 100 parts by weight of the fluorine
rubber component 11, the resistance value was not more than 40 N and particularly
favorable slidability was achieved. Therefore, it is particularly favorable that the
content of the particulate resin 12 in the composition for a sealing member 10 is
not less than 5 parts by weight.
[0090] Meanwhile, in any of the samples according to Comparative Examples1-1, 1-2, and 1-4
to 1-12 in which the configuration is different from that in this embodiment, the
resistance value exceeds 70 N and favorable slidability was not achieved. Therefore,
it was confirmed that in the sealing member 20 according to this embodiment, slidability
higher than that of any of the sealing members according to Comparative Examples could
be achieved.
3.2 Examples 2-1 to 2-9
[0091] In Examples 2-1 to 2-9, samples of the sealing member 20 were prepared by molding
the composition for a sealing member 10 having a different content of carbon under
the same conditions as those in Examples 1-1. Then, the slidability of each sample
was evaluated similarly to Examples 1-1 to 1-5 and Comparative Examples 1-1, 1-2,
and 1-4 to 1-12 described above.
[0092] Table 2 shows the evaluation results of the samples according to Examples 2-1 to
2-9. Further, Table 2 shows the contents (parts by weight) of carbon and the lubricant
1 of each sample. Note that in Example 2-1, the content of carbon is 0 part by weight,
i.e., carbon is not used.
[Table 2]
|
Example 2-1 |
Example 2-2 |
Example 2-3 |
Example 2-4 |
Example 2-5 |
Example 2-6 |
Example 2-7 |
Example 2-8 |
Example 2-9 |
Fluorine rubber component |
100 |
100 |
100 |
100 |
100 |
100 |
100 |
100 |
100 |
Carbon |
0 |
10 |
20 |
30 |
40 |
50 |
60 |
70 |
80 |
Lubricant 1 |
10 |
10 |
10 |
10 |
10 |
10 |
10 |
10 |
10 |
Slidability |
B |
B |
B |
B |
A |
A |
A |
A |
A |
[0093] As shown in Table 2, in any of the samples according to Examples2-1 to 2-9, the resistance
value was not more than 50 N and favorable slidability was achieved. Further, in Examples
2-5 to 2-9 in which the content of carbon was not less than 40 parts by weight, the
resistance value was not more than 40 N and particularly favorable slidability was
achieved.
4. Configuration Example of Sealing Member 20 4.1 Overview
[0094] As an example of the sealing member 20 according to this embodiment, an example in
which the sealing member 20 includes a seal ling having high hardness will be described.
Specifically, in the sealing member 20 according to this configuration example, the
Shore A hardness measured using the surface, which serves as the sliding surface,
of the surface layer portion 23 as the pressing surface is not less than 80.
[0095] That is, the composition such as the amount of carbon in the composition for a sealing
member 10 is determined so that the Shore A hardness of the sealing member 20 is not
less than 80. By molding such a composition for a sealing member 10 in a ring shape,
the sealing member 20 having high hardness is obtained.
[0096] The sealing member 20 having high hardness can be suitably used as, for example,
an oil seal for a hydraulic device. That is, in the hydraulic device, it is effective
to use the sealing member 20 having high hardness in order to suppress a decrease
in sealing property due to deformation or damage by high hydraulic pressure. Further,
the sealing member 20 is particularly suitable for sealing between members that reciprocate.
[0097] Examples of the hydraulic device capable of effectively using the sealing member
20 having high hardness include a continuously variable transmission (CVT) including
a pulley, which includes a shaft that reciprocates and housing. Hereinafter, an example
in which the sealing member 20 having high hardness is used in a continuously variable
transmission will be described with reference to Figs. 5A to 7.
4.2 Sealing Member 20 for Continuously Variable Transmission
[0098] Fig. 5A is a plan view of the sealing member 20 used in a continuously variable transmission.
Fig. 5B is a cross-sectional view of the sealing member 20 taken along the line A-A'
in Fig. 5A. The sealing member 20 is formed in a ring shape centered on a central
axis E. Further, the sealing member 20 includes the body portion 22 and the surface
layer portion 23 that covers the body portion 22.
[0099] Fig. 6 is a cross-sectional view showing an operation of incorporating the sealing
member 20 into a shaft 30 and a housing 40. The shaft 30 includes a groove portion
31 provided over the entire circumference thereof. Further, in the housing 40, an
insertion hole in which the shaft 30 is inserted is provided.
[0100] The inner diameter of the sealing member 20 is slightly smaller than the diameter
of a bottom surface 32 of the groove portion 31 of the shaft 30. For this reason,
the sealing member 20 is fitted in the groove portion 31 of the shaft 30 while being
slightly expanded in the radial direction. As a result, the inner peripheral surface
of the sealing member 20 is in close contact with the bottom surface 32 of the groove
portion 31 of the shaft 30.
[0101] Then, the shaft 30 in which the sealing member 20 is mounted in the groove portion
31 is inserted into the housing 40 from the side of an end surface 42. The outer diameter
of the sealing member 20 mounted in the groove portion 31 of the shaft 30 is slightly
larger than the inner diameter of the housing 40. For this reason, it is necessary
to compress and deform the sealing member 20 in the radial direction.
[0102] The housing 40 includes a chamfered portion 43 that connects the end surface 42 and
an inner peripheral surface 41 to each other. For this reason, when the shaft 30 is
inserted into the housing 40 from the side of the end surface 42, the sealing member
20 eventually reaches the end surface 42 of the housing 40, and the sealing member
20 is brought into contact with the chamfered portion 43 of the housing 40.
[0103] In this state, a pressing force is further applied to the shaft 30 to push the shaft
30 into the housing 40 as it is. As a result, the sealing member 20 enters the housing
40 while being compressed and deformed in the radial direction by receiving a radially
inward pressing force from the chamfered portion 43 of the housing 40.
[0104] Then, the sealing member 20 reaches the inner peripheral surface 41 of the housing
40, and the shaft 30 is further pushed to a predetermined position, thereby finishing
the insertion of the shaft 30 into the housing 40. As described above, it is possible
to smoothly insert the shaft 30 into the housing 40 only by the operation of pushing
the shaft 30 to the housing 40.
[0105] In this embodiment, since the sealing member 20 is covered with the surface layer
portion 23, the sliding resistance between the sealing member 20 and the housing 40
when the shaft 30 is inserted into the housing 40 is reduced. This makes it easy to
insert the shaft 30 into the housing 40.
[0106] Specifically, in the sealing member 20, the sliding resistance when passing through
the chamfered portion 43 of the housing 40 is reduced by not less than 30% as compared
with the sealing member formed of only the fluorine rubber 21. Further, in the sealing
member 20, also the sliding resistance when sliding along the inner peripheral surface
41 of the housing 40 is reduced by not less than 30%.
[0107] Fig. 7 is a cross-sectional view showing the state where the sealing member 20 is
incorporated into the shaft 30 and the housing 40. The sealing member 20 shown in
Fig. 7 is compressed and deformed in the radial direction by being sandwiched between
the shaft 30 and the housing 40. Therefore, an elastic force of trying to expand in
the radial direction is generated in the sealing member 20.
[0108] For this reason, the sealing member 20 presses the inner peripheral surface to the
bottom surface 32 of the groove portion 31 of the shaft 30 by the elastic force of
trying to expand in the radial direction, and presses the outer peripheral surface
to the inner peripheral surface 41 of the housing 40. As a result, the sealing member
20 is capable of sealing between the shaft 30 and the housing 40.
[0109] When the shaft 30 reciprocates in relation to the housing 40, the outer peripheral
surface of the sealing member 20 slides in relation to the inner peripheral surface
41 of the housing 40 while keeping contact therewith. Thus, the sealing property between
the shaft 30 and the housing 40 is maintained. In the sealing member 20, the body
portion 22 has rubber elasticity, a high sealing property can be achieved.
[0110] Further, in the sealing member 20, the outer peripheral surface, which is a sliding
surface that is in contact with the housing 40, includes the surface layer portion
23. For this reason, the sliding resistance between the outer peripheral surface of
the sealing member 20 and the inner peripheral surface 41 of the housing 40 is reduced.
As a result, the drive loss when the shaft 30 reciprocates in relation to the housing
40 is reduced.
[0111] Note that in the sealing member 20, it is favorable that a parting line that can
be formed at the time of molding is not present on the outer peripheral surface, which
is a sliding surface. As a result, the sliding resistance between the outer peripheral
surface of the sealing member 20 and the inner peripheral surface 41 of the housing
40 is further reduced. Note that the sliding surface of the sealing member 20 is not
limited to the outer peripheral surface, and may be the inner peripheral surface or
side surface.
4.3 Example
4.3.1 Preparation of Sample
[0112] A sample A of the sealing member 20 according to Example and a sample B of a sealing
member according to Comparative Example, which was formed of only the fluorine rubber
21 in a shape similar to that of the sample A, was prepared.
[0113] Fig. 8 shows an infrared spectrum obtained as a result of infrared absorption analysis
of the surface of the sample A. In the infrared spectrum shown in Fig. 8, a peak of
absorbance of silicone is observed in a region surrounded by broken lines with a wave
number of approximately 1100 cm
-1. In accordance therewith, it has been confirmed that the particulate resin 12 is
present on the surface of the sample A.
4.3.2 Slidability Evaluation
[0114] Slidability evaluation was performed on the samples A and B. For the slidability
evaluation, the housing 40 having the inner diameter of 161 mm and the shaft 30 corresponding
thereto were used. That is, in this slidability evaluation, the housing 40 is used
as a counterpart material and the outer peripheral surface of each of the samples
A and B is caused to slide along the inner peripheral surface 41 of the housing 40.
[0115] In the slidability evaluation, the resistance value (load) when the shaft 30 in which
each sample is mounted is caused to slide in relation to the housing 40 in oil was
measured. The temperature of the oil was 80°C. Further, the hydraulic pressure of
the oil was changed in the range of 1 to 6 MPa, and the resistance values at 1 MPa,
3 MPa, and 6 MPa were measured.
[0116] Fig. 9 is a graph showing the measurement results of the resistance value. In Fig.
9, the horizontal axis indicates the hydraulic pressure (MPa) and the vertical axis
indicates the relative value of the resistance value. As shown in Fig. 9, at any hydraulic
pressure, the resistance value of the sample of the sealing member 20 according to
Example is lower by not less than 30% than that of the sample of the sealing member
according to Comparative Example.
[0117] As a result, it was confirmed that in the sealing member 20, the sliding resistance
could be significantly reduced by the action of the surface layer portion 23. Further,
in the sealing member 20, it was confirmed that the effect of reducing the sliding
resistance even in the high hydraulic pressure was maintained. This is considered
to be due to the Shore A hardness of the sealing member 20 being not less than 80.
4.3.3 Examination of Surface Roughness Rz
[0118] Regarding the surface roughness Rz of the counterpart material and the surface roughness
Rz of the sliding surface of the sealing member 20, the conditions under which particularly
excellent slidability and sealing property could be obtained were examined. In this
embodiment, the surface roughness Rz is defined in accordance with the JIS standard
(JIS B 6001-1982).
(1) Surface Roughness Rz of Counterpart Material
[0119] As the counterpart material, the housing 40 in which the surface roughness Rz of
the inner peripheral surface 41 differs was prepared. Specifically, the surface roughness
Rz of the counterpart material was 0.1 z, 0.5 z, 3.0 z, 6.0 z, 8.0 z, 13.0 z, 18.0
z, and 24.0 z. The surface roughness Rz of the outer peripheral surface, which is
a sliding surface of the sealing member 20, was 6.0 z.
[0120] The slidability evaluation of the sealing member 20 with respect to each counterpart
material was performed. In the slidability evaluation, the resistance value was measured
similarly to the above. As a result, in the case of the counterpart material having
the surface roughness Rz of not less than 0.5 z, a particularly low resistance value
was obtained. As described above, it can be seen that in the sealing member 20, excellent
slidability can be achieved even if the surface roughness Rz of the counterpart material
is large.
[0121] Meanwhile, in the case of the counterpart material having the surface roughness Rz
of 0.1 z, the resistance value was slightly higher. This is considered because the
surface of the counterpart material is too smooth, making it difficult to form an
oil film between the surface of the counterpart material and the sliding surface of
the sealing member 20. From this viewpoint, it is favorable that the surface roughness
Rz of the counterpart material is not less than 0.5 z.
[0122] Further, the sealing property between each counterpart material and the sealing member
20 was evaluated. As a result, in the range from 0.1 z to 13.0 z of the surface roughness
Rz of the counterpart material, a particularly high sealing property was achieved.
As described above, it can be seen that in the sealing member 20, even in a range
in which the surface roughness Rz of the counterpart material is high, an excellent
sealing property can be achieved.
[0123] Meanwhile, in the case of the counterpart material having the surface roughness Rz
of 18.0 z, the sealing property was slightly lower. In the case of the counterpart
material having the surface roughness Rz of 24.0 z, the sealing property was further
lowered. From this viewpoint, the surface roughness Rz of the counterpart material
is favorably not more than 18.0 z, and more favorably not more than 13.0 z.
[0124] Further, as described above, in the sealing member 20, even in the case where the
surface roughness Rz of the counterpart material is large, excellent slidability and
sealing property can be easily achieved. Therefore, using the sealing member 20 eliminates
the necessity for processing such as mirror polishing for smoothing the counterpart
material. As a result, it is possible to reduce the production cost of the counterpart
material.
(2) Surface Roughness Rz of Sliding Surface of Sealing Member 20
[0125] The sealing member 20 in which the surface roughness Rz of the sliding surface differs
was prepared. Specifically, the surface roughness Rz of the sliding surface of the
sealing member 20 was 0.1 z, 0.5 z, 1.0 z, 3.0 z, 6.0 z, 8.0 z, 10.0 z, and 15.0 z.
The surface roughness Rz of the counterpart material was 6.0 z.
[0126] The slidability evaluation of each sealing member 20 with respect to the counterpart
material was performed. In the slidability evaluation, the resistance value was measured
similarly to the above. As a result, in the case of the sealing member 20 in which
the surface roughness Rz of the sliding surface is not less than 0.5 z, a particularly
low resistance value was obtained. As described above, it can be seen that in the
sealing member 20, excellent slidability can be achieved even if the surface roughness
Rz of the sliding surface is large.
[0127] Meanwhile, in the case of the sealing member 20 in which the surface roughness Rz
of the sliding surface is 0.1 z, the resistance value was slightly higher. This is
considered because the sliding surface of the sealing member 20 is too smooth, making
it difficult to form an oil film between the sliding surface of the sealing member
20 and counterpart material. From this viewpoint, it is favorable that the surface
roughness Rz of the sliding surface of the sealing member 20 is not less than 0.5
z.
[0128] Further, the sealing property between the counterpart material and each sealing member
20 was evaluated. As a result, in the range from 0.1 z to 8.0 z of the surface roughness
Rz of the sliding surface of the sealing member 20, a particularly high sealing property
was achieved. As described above, it can be seen that in the sealing member 20, even
in a range in which the surface roughness Rz of the sliding surface is high, an excellent
sealing property can be achieved.
[0129] Meanwhile, in the case of the sealing member 20 in which the surface roughness Rz
of the sliding surface is 10.0 z, the sealing property was slightly lower. In the
case of the sealing member 20 in which the surface roughness Rz of the sliding surface
is 15.0 z, the sealing property was further lowered. From this viewpoint, the surface
roughness Rz of the sliding surface of the sealing member 20 is favorably not more
than 10.0 z, and more favorably not more than 8.0 z.
[0130] Further, as described above, in the sealing member 20, even in the case where the
surface roughness Rz of the sliding surface is large, excellent slidability and sealing
property can be easily achieved. Therefore, using the sealing member 20 eliminates
the necessity for processing such as mirror polishing for smoothing the sliding surface.
As a result, it is possible to reduce the production cost of the sealing member 20.
4.4 Other Applications of Sealing Member 20 Having High Hardness
[0131] The sealing member 20 is very useful for applications that require high hardness
in addition to the hydraulic device.
[0132] For example, the sealing member 20 is effective not only as an oil seal but also
as a gas seal. For this reason, the sealing member 20 can be suitably used as a seal
of the rotation shaft of a compressor, a seal of a gas valve, a seal of a gas regulator,
or the like.
[0133] Further, the sealing member 20 is also effective as a seal of fuel such as gasoline.
For this reason, the sealing member 20 can be suitably used in, for example, a fuel
injection pump.
[0134] Further, the sealing member 20 can be suitably used as a dust seal or a drip-proof
seal in an apparatus such as an industrial robot.
5. Other Embodiments
[0135] Although an embodiment of the present invention has been described above, it goes
without saying that the present invention is not limited to only the above-mentioned
embodiment and various modifications can be made without departing from the essence
of the present invention.
Reference Signs List
[0136]
- 10
- composition for a sealing member
- 11
- fluorine rubber component
- 12
- particulate resin
- 12a
- compatible portion
- 12b
- lubrication portion
- 20
- sealing member
- 21
- fluorine rubber
- 22
- body portion
- 23
- surface layer portion
- 30
- shaft
- 31
- groove portion
- 40
- housing
- M
- mold